The principal goals of thrombolytic therapy for stroke are early restitution of cerebral blood flow, reduction of ischaemia, and attenuation of neurological disability through lysis of an occluding thrombus and consequent rapid restoration of circulation in the affected territory. Therapy should be initiated as soon as possible, at least within 4-6 h of stroke onset, to prevent major infarction and to salvage the hypoperfused but potentially viable zone adjacent to the central ischaemic area known as the ischaemic penumbra. This survey focuses on the safety and efficacy of thrombolytic therapy in acute ischaemic stroke in clinical trials. The results of two successful major randomized studies using tissue plasminogen activator (t-PA) were recently published. Intravenous thrombolysis seemed to be effective in improving functional and neurological outcome in a clearly defined subgroup of patients meeting the inclusion criteria of the studies. However, the identification of those patients proved to be difficult and depended on expertise in recognizing the early infarction signs on initial computed tomography. Since treating ineligible patients is associated with an unacceptable risk of intracranial bleeding complications and death, intravenous thrombolysis should only be performed at selected centres in selected patients.